Smartphones and other types of portable, hand-held computing devices, such as tablet computers, are in widespread use today, most often in connection with entertainment, communications and office productivity. Most smartphones include a camera, and applications have been developed for using the camera to read barcodes. In a typical known application an image feed from the camera is displayed on the display screen of the smartphone to assist the user in aiming the field of view of the camera towards the barcode and ensuring that the entire barcode is within the image captured by the camera.